One of YouTube's biggest channels has lost almost 300,000 subscribers in two days after its creators announced plans to trademark a popular video format.

Brothers Benny and Rafi Fine make "reaction videos" in which people are shown clips or presented with objects and respond.

They had accumulated more than 14 million subscribers.

But this week they ran into trouble after announcing a licensing scheme called React World, which would force other users to share ad revenue in return for using the "react" title, and assets like graphics and music.

Image Caption:The Fine Bros YouTube page had more than 14 million subscribers

They filed an application to trademark terms including "Kids React", "Adults React", and "Celebrities React", as well as the word "react" itself.

The filing said this would cover "programmes and webisodes via the internet in the field of observing and interviewing various groups of people".

The plan sparked a backlash which led to their subscriber numbers dropping suddenly.

As a result, the pair performed a dramatic U-turn on Tuesday morning, rescinding all "react" trademarks and applications.

They said in a blog post that their intentions were "pure" but acknowledged that viewers had valid concerns.

It read: "We realise we built a system that could easily be used for wrong. We are fixing that.

"The reality that trademarks like these could be used to theoretically give companies (including ours) the power to police and control online video is a valid concern, and though we can assert our intentions are pure, there’s no way to prove them."

The brothers have previously had videos that copy their format removed from YouTube.

The post added that "it makes perfect sense for people to distrust our motives here" but said they will regain their viewers' trust.